1. Field of the Invention
The invention relates to a laser oscillator and is based on a tunable laser for the simultaneous or alternating production of several wavelengths.
On the basis of numerous applications of tunable lasers with several wavelengths, such as multiphoton excitation, CARS (Coherent Antistokes Raman Scattering) or DIAL (Differential Absorption LIDAR), in the past various different laser configurations have been developed for simultaneously or alternately producing several wavelengths using the same laser system.
Among the hither to known processes there is no configuration permitting both the simultaneous and alternate operation without considerable efficiency losses.
2. Description of the Related Art
Simple beam displacement by a parallel plate, such as was described by Brechignac et al in N. D. Hung, P. Brechignac, Applied Optics, vol. 27, p. 1906, 1988, only permits alternating operation, which is additionally restricted by a long switching time.
The hitherto known arrangements suffer from the following disadvantages: greatly restricted selection possibility with regards to the different wavelengths and types of resonators or cavities (choice not independent, choice restricted to closely juxtaposed wavelengths, non-achromatism), imprecise determinability of the wavelengths, difficulties in adjusting the beams, different polarization directions, considerable losses due to insertion, or in the simultaneous operating mode instabilities and losses of efficiency as a result of the significant competition between the two emitted modes.
The problem of the invention is to use a tunable laser system for solving the aforementioned problems in the case of space and time superimposing of the different beams, whilst allowing a choice between the two operating modes without any modification to the arrangement.
This problem is solved by the features of the main claim, in conjunction with the appropriate features of the subclaims.